Electromagnetic (EM) radiation path modifying devices, such as optical devices are well known and widely used for controlling the path of electromagnetic radiation. There are many types of such device in general use. For example, a converging lens is used to collect a wide beam of radiation and ‘bend’ or converge it toward a point, called a focal point, as illustrated schematically in FIG. 1A. A diverging lens has a negative focal point and causes the parallel rays of an incoming beam of radiation to ‘bend’ in the opposite direction, thereby causing them to become more spread apart at the output of the device, as illustrated schematically in FIG. 1B. Both the converging and diverging lenses operate on the principle of refraction which is defined as the change in direction of a wave passing from one medium to another caused by its change in speed and the EM radiation path modifying properties of such devices are defined by their geometry, with the refractive index thereof being fixed within a physical device.